Demolition firing device



Jan. 29, 1957 F. A. CLARY, JR

mamouuou FIRING DEVICE 2 Sheets-Sheet 1 Filed March 13, 1946 grvuc/Mm IA. Clary, Jr:

Jan. 29, 1957 F. A. CLARY, JR 2,779,276

DEMOLITION FIRING DEVICE Filed March 13, 1946 2 Sheets-Street 2 83 H4 H5 H3 I16 I03 I04 84 98 I22 $66 97 no I05 95 43 9 B o "2 1 Ill 3-, 1' 7g 53 78 I 9| 1 '8? I09 I02 lol 37 5 4 33 g United States Patent-O This invention relates generally to a demolition firing device and more specifically to a demolition firing device particularly adapted for use with underwater ordnance.

In many cases, such as in amphibious warfare, it is necessary to remove underwater hazards in shallow water to permit landing parties to go safely ashore. The obvious way of disposing of such underwater hazards is by blowing same up. In placing charges against obstacles under water, the most dangerous and time-consuming task is to connect them together to insure simultaneous detonation. This is particularly the case where such charges must be planted under enemy fire.

It is an object of'the present invention to provide a new and improved pressure actuated detonating device incorporating an electrolytic cell time delay means in which the cell locks the pressure actuated detonating device against 7 operation until the cell has been activated for a predetermined time.

It is furthermore an object of the present invention to provide a pressure actuated detonating device incorporating an electrolytic cell time delay means in which the anode plate of the cell is protected by a locking device from being broken by excessive shocks such as would occur during countermining. I

It is moreover an object of the present invention to provide a pressure actuated detonating device incorporating an electrolytic cell time delay means in which an automatic locking means is provided between the actuating means for the device and the electrolytic cell, the automatic locking means being operated by the electrolytic cell and effective prior to arming of the device,

Other objects, advantages, and improvements will be apparent from the following description, taken in connection with the accompanying drawings, in which:

Fig. l is a view of the pressure actuated demolition firing device attached to a demolition charge;

Fig. 2 is a sectional view through the pressure actuated detonatingdevice and the attached electrolytic arming cell and showing-in particular the locking means between the device and the electrolytic cell in locked position;

Fig. 3 is a sectional view on a reduced scale taken on the section line 3--3 of Fig. 2 showing the firing pin engaged by the catch spring;

Fig. 4 is a view on the section line 44 of Fig. 2 showing the interior construction of the arming cell;

Fig. 5 is a view similar to Fig. 2 but showing the pressure responsive diaphragm in operated position, the catch spring released from the firing pin, the firing pin infiring position, the locking means between the device and the electrolytic cell in unlocked position, the cap removed from the electrolytic arming cell, and the electrolytic arming cell in armed or released position;

Fig. 6 is a sectional view on the section line 6-6 of Fig. 2 showing the safety block and the safety pin of the electrolytic arming cell in position; and

Fig. 7 is a sectional view on the section line 77 of Fig. 2 showing the plunger of the electrolytic arming cell and the locking balls of the locking means intermediate the device and the electrolytic arming cell in position.

Referring now to the drawings and to Fig. 2 in particular, it will be seen that the principal part of the pressure actuated detonating device is a body comprised by an end disc 10, a concentric integral barrel member 15 and a hexagonal boss 14 intermediate and integral with the end disc 10 and the barrel member 15. The end disc 10 has a central hole 18 therethrough and the barrel member 15 has a concentric bore 16 therethrough, the latter being threaded at its outer end at 17. Reinforcing ribs 1919 are integral with the hexagonal boss 14 and the barrel member 15 and extend for about three-quarters of the length of the barrel. The ribs 1919 are provided with holes 21 adjacent their outer ends for the reception of a wire 22 to facilitate attachment of the detonating device to a demolition charge 20, as shown in Fig. 1.

An integral boss 23 having its outer end rounded is formed on the upper side of the barrel member 15, this boss being likewise integral with the hexagonal boss 14 on the end disc 10. Centrally of the boss 23 there is formed a threaded bore 24 and a concentric bore 26 extends radially through the wall of the barrel member 15 into the bore 16 therethrough, the bore 24 forming a seat for the locking ball 25. A hollow cylinder 28 is threaded externally at its lower end at 27, for mounting in the threaded bore 24 in the boss 23, and internally at its upper end at 29, for attachment of the arming cell thereto, as will be later described. At the bottom of the bore 24 there is positioned a rubber diaphragm 30, a flat retaining ring 31 being interposed between the lower end of the hollow cylinder 28 and the diaphragm. The diaphragm 30 constitutes a yieldable retaining means for the locking ball 25 and also seals the bore 16 through the barrel member 15 against the ingress of sea water. In the lower end of the hollow cylinder 28 and resting on the diaphragm 30 there is positioned a cylindrical safety block 32, the latter having a loose fit in the hollow cylinder. The cylindrical safety block 32 has a diametral slot 33 on its upper face. Adjacent the lower end of the hollow cylinder 28 and above the lower threads 27 therein, there are formed two (2) pairs of diametrically positioned holes 34-34. A safety pin 35 is located in one pair of the holes 34-34 and this pin projects through the diametral slot 33 in the safety block 32, holding the safety block in position against the diaphragm 30.

The end disc 10 of the body has an outwardly disposed circumferential flange 11 which is threaded on its periphery at 12 in the plane of the disc and at its outer end is faced to form a shoulder 13.

A snap diaphragm 36 is in the form of a domed and stressed phosphor bronze disc and of the proper diameter to fit loosely within the shoulder 13 in the outer face of the circumferential flange 11 on the end disc 10. By reason of the specific mounting employed the dome may be forced through the plane of the disc and the disc thereby deformed so that the dome inverts itself and protrudes from the other side of the disc. In the initial position (unoperated or cocked), Fig. 2, the diaphragm is internally stressed and is adapted to reversely flex with a strong snap action to the position shown on Fig. 5 by a predetermined pressure applied thereto. When the diaphragm is in the position shown on Fig. 2, a pressure, such, for example as nine (9) pounds per square inch, on its outer convex face will cause it to deflect and snap through a plane position and assume a dished concave position. The elastic snap of the diaphragm in the example from the domed to the dished position exerts a force of approximately fifty (50) pounds per square inch. However, a pressure of approximately seventy (70) pounds per square 3 inch. is required to return the diaphragm from the .position shown on Fig. 5 to the initial cocked position.

in order to protect the snap diaphragm 36 and the firing pin mechanism from the ingress of sea water a thin rubber diaphragm 37 is positioned over the outer face of the snap diaphragm, this rubber diaphragm being of the same diameter as the flange 11 on the end disc of the body. A flat retaining ring 38 of the same outer diameter as the rubber diaphragm 36 is secured on the outer face of the latter, as by any suitable adhesive means.

The snap diaphragm 36, rubber diaphragm 37, and the retaining ring 38 are secured in place by a cast diaphragm cover 40. This cover has a convex face which is reticulated to form a grille or lattice work 39. On the periphery of the diaphragm cover 40 there is formed 'an integral circumferential flange 41 which is provided with integral diametrically spaced lugs 4-3 for-engagement by a suitable wrench and is also provided with internal threads 42 for engagement with the threads 12 on the periphery of the end disc 10. At the bottom of the threads 42 there is formed in the inner wall of the circumferential flange 41 a shoulder -44 for reception of the retaining ring '38 and the rubber diaphragm 3'7. The cover 40 compresses the rubber diaphragm 37 between the retaining ring 38 and the face of the flange ll. and thereby seals the chamber on the interior of the flange 11 against water leakage.

A firing pin 45 is of generally rod-like shape and adjacent its rear end has a circumferential groove i6 fo'r reception of a catch spring 52 of greater diameterof crosssection than the width of the groove whereby the spring is adapted to be forced free of the groove by a predetermined pressure applied thereto. Approximately midway of the firing pin 45 there is formed an integral shoulder 47 having a plane face towards the outer end of the firing pin and a frusto-conical inner face 48. Adjacent the inner end of the firing pin there is formed a second and disc like integral shoulder d9, this being of the same diameter as the middle shoulder 47, and the two constituting a guide for the firing pin in the bore 16 through the barrel member 15. The inner end of the firing pin'is rounded at 51. -In assembly, a coiled compression positioning spring "50 is placed around the cylindrical outer end of the firing pin 45 and the pin and spring are inserted in the bore 16 through the barrel member 15, thccylindrical outer end of the firing pin projecting through the central hole 18 through the end disc '16. With the safety block 32 and the safety pin 35 removed, the locking ball 25 will fall by its own weight, if the body 10 is held with the hollow cylinder 28 positioned vertically upwardly; as the firing pin 45 and the compression spring 50 are inserted in'the bore 16 through the barrel member 15, the, middle shoulder &7 slides under the bore 26 through the .side wall of the barrel member, in which the locking ball 25 is positioned, passes the latter, and the positioning spring Silis compressed between'thc bottom 'ofithe bore and'the .shoulder 47 Landthe cylindrical'outer end of the firing pin projects through thecentral hole 18 in the end disc 10 into abutting relation with the snap diaphragm 36, th'e compression spring 50 being lightly loaded in this position. A catch spring 52 consists of two parallel spring rods united at each pair of ends by beaded straps 53. The catch spring 52 is engaged in-the groove 46 adjacent the outer end of the firing pin 45 by spreading apart the parallel spring rods 52-52 and, when so engaged, abuts the outer face of the end disc 10 to limit inwardmovementofthe firing pin 45.

When the demolition firing device is .notrin .use, the bore 16 through the barrel member 14 is preferably closed by a shipping plug (not shown). .In armingthe demolition firing device, the shipping plug is removed and replaced by an adapter 66. The latter comprises seriatim an outer threaded hub 57 having external threads to engage with the internal threads 17 in the inner end of the bore 16 through thebarrelrnember .15, an integral central disc 60 which is knurled onits periphery, an inner integral threaded hub 62, which is .of slightly greater diameter and has coarser threads thereon than the outer threaded hub 57, and an integral elongated extension 64 of reduced diameter, the latter terminating in a shoulder 65. An axial bore 59 is provided through the outer threaded hub 57, the central disc 6i), and part of the way through the inner threaded hub 62; a concentric axial bore 66 of reduced diameter continues through the inner threaded hub 62, the elongated extension 64, and the integral shoulder 65 on the latter. The face of the outer threaded hub 57 is provided with a shoulder 58, concentrically positioned with respect to the axial bore 59 through the hub. A gasket 61 is provided around the outer threaded hub 57 and intermediate the central disc and the face of the barrel member 15; similarly, an identical gasket 63, except for the inner diameter, is provided around the inner threaded hub 62 and abutting the central disc 60 of the adapter.

A percussion priming cap 67 has an end disc 68, this cap being of the proper diameter to fit within the axial bore 59 through the outer threaded hub 57 of the adapter 60 with the disc 68 against the shoulder 58 on the face of the adapter.

Mounted on the elongated extension 64 of the adapter 60 there is a flame ignited blasting cap 69, this cap having its exposed end crimped over the shoulder on the inner end of the adapter.

Around the blasting cap 69 there 'is positioned a cylindrical booster casing 79. in the casing 70 there is mounted a hollow cylindrical spacer 72 in the bore of which the blasting cap 69 is received. Intermediate the spacer 72 and the outer end of the cylindrical casing 70 there is secured a metal insert 73. The insert 73 is held in the cylindrical casingitl by a rolled-in groove 71 formed in the latter and this insert is provided with internal threads for engagement with the threads on the inner threaded hub 62 of the adapter 60. The blasting cap 69 and the cylindrical spacer '72 are substantially coextensive in length and at their outer terminal there is provided a shock absorber '74 in the form of a cylindrical pad of commercial felt of the proper diameter to have a snug fit within the cylindrical casing 70. An end cap is secured over the outer end of the cylindrical casing 70 as by a sweated joint. In the space within the cylindrical casing 70 intermediate the shock absorber 74 and the end cap 75 there is placed the booster charge 76 comprising approximately 5 .8 grams of tetryl or some similar high explosive.

The electrolytic arming cell unit is mounted in a cylindrical casing 78 having a lower central boss 77 with external threads for engagement with the internal threads on the hollow cylinder 28. At approximately its midseetion the cylindrical casing 78 is formed with an external shoulder 79, the casing continuing above this shoulder as a hollow cylindrical extension 80. The hollow cylindrical extension 86 is provided with a row of areuately spaced'holes 82'for admission of the sea water and terminates in a beaded over flange 84 for holding the electrode assembly of the arming cell in place, as will be later described. Immediately above the external shoulder 79 the hollow cylindrical extension is formed with a row of left-hand threads 81. The cylindrical casing 78 is normally enclosed by a cylindrical cap 85 which has -a row of lefthand threads 86 on the lower inner periphery "of its skirt for coaction with the threads '81 on the hollow cylindrical extension 80 of the-casing. A gasket 87 of leather, or other suitable material, is interposedbetweenthe bottom of the skirt of the cap 85 and theexternal shoulder 79 on the cylindrical casing Approximately one-third of the way from its top the inner wall of the skirt of the cap 85 is provided with a shoulder 88. An open bottom cylindrical screen 89 is of the proper diameter and fitted within the cap 85 and against .the shoulder ,88. seen-a the top of the cap there is placed a mass 90 of Intermediate the screen a suitable desiccating agent, silica gel being preferred for this purpose. 7

A central bore 93 in the hollow cylindrical casing 78 provides space for the plunger mechanism, as will be later described. The central bore 93 terminates short of the bottom of the hollow cylindrical casing 78 and an inverted frusto-conical bore 91 continues through the bottom of the hollow cylindrical casing and the lower central boss 77 thereon. On the inner wall of the frustoconical bore 91 and just below the juncture of the central boss 77 with the hollow cylindrical casing 78 there is formed a groove 92, this groove being shaped as a toroid truncated along a surface approximately parallel to the axis of the toroid and the groove being adapted for the reception of locking balls 100-100, as will be later described. Co-planar with the external shoulder 79 on the hollow cylindrical casing 78 there is formed an internal shoulder 94. Above the shoulders 79 and 94 the bore 93 in the hollow cylindrical casing 78 is enlarged by a counterbore 96 to form a sea water chamber. Adjacent the top of the hollow cylindrical extension 80 of the casing '78 and above the arcuately spaced holes 82 therein, the counterbore 96 is enlarged by a second counterbore 98 of still greater diameter, the juncture of the counterbores 96 and 98 forming a shoulder 97 which supports the electrode assembly of the sea cell, as will be later described.

The hydrostat mechanism has as its principal moving parts a plunger 108 and a frusto-conical sleeve 99, the latter being adapted to reciprocate within the frusto-conical bore 91 through the bottom of the hollow cylindrical casing "78 and the central boss 77 thereon. The sleeve 99 has an axial bore 101 which, however, stops short of the bottom or the sleeve. Transversely of the sleeve 99 a cross bore 102 intersects the axial bore 101. Two locking balls'100100 are positioned, one partially in each end of the cross bore 101 through the sleeve 99 and the toroidal groove 92 around the wall of the frustoconical bore 91 through the lower central boss 77. With the locking balls 100--100 in position in the respective ends of the transverse bore 102 and the toroidal groove 92 around the wall of the frusto-conical bore 91 through the central boss 77, the frusto-conical sleeve 99 is locked against reciprocation, the upper base of this sleeve being flush with the bottom of the central bore. 93 through the hollow cylindrical casing 78 and the lower base of the sleevebeing positioned adjacent the cylindrical safety block 32 in the hollow cylinder 26 and spaced a distance therefrom less than the diameter of the locking ball 25.

The principal component of the plunger mechanism has an enlarged head 104, a reduced section 106, and a concentric cylindrical plunger section 108, an undercut shoulder 105 being formed between the head 104 and the reduced section 106, and similarly an undercut shoulder 107 being formed between the reduced section 106 and the cylindrical plunger extension 108. The cylindrical extension 108 is adapted to be normally positioned intermediate the locking balls 100--100 and to force same outwardly through the ends of the transverse bore 102 in the frusto-conical sleeve 99 and into the toroidal groove 92 in the wall of the frusto-conical bore 91 through the lower central boss 77. i

The plunger is biased upwardly by a frusto-conical compression spring 109 which is positioned with its base on the bottom of the central bore 93 in the casing 78 and itsupper and inner coil against the shoulder 107 intermediate the reduced section 106 and the cylindrical extension 108. The compression spring operates on a frusto-conical diaphragm 110. The diaphragm 110 is secured at its inner periphery against the shoulder 105 intermediate the enlarged head 104 and the reduced section 106 of the plunger by a retaining ring 111,'the shoulder ltl'linterrnediate the reduced section 106 and the' cylindrical extension 108 being beaded overtg hold the retaining ring 111 and the inner periphery of the diaphragm 110 in place; similarly, the outer periphery of the diaphragm 110 is secured in place against the shoulder 94 intermediate the central bore 93 in the cylindrical casing 78 and the counterbore 96 in the cylindrical extension of the casing 78 by a retaining ring 112, the shoulder 94 being beaded over at to hold the retaining ring and the outer periphery of the diaphragm in place.

The elements of the electrolytic arming cell comprise two cathode washers 119119 of silver chloride and an anode disc 122 of magnesium, the two cathode washers being positioned on either side of the anode disc 122. The two cathode washers 119119 have central apertures in which are positioned bushings 120 of a phenolic condensation product; similarly, the anode disc 122 has a central aperture in which there is secured an eyelet 126 preferably of brass and tin plated, the eyelet being beaded over at its ends on either side of the disc. Intermeditae either end of the eyelet 126 and the corresponding cathtode washer there is positioned an insulating Washer 121, the latter preferably being made of parachute cloth impregnated with a phenolic resin compound. Dished spring washers 11S118, preferably of silver, are positioned on the exposed faces of the cathode washers 119119. The cathode Washers 119119 and the anode disc 122 are held in assembled relationship by a central tube 117, also preferably of silver, which passes through the dished spring washers 118118, bushings 120--120, insulating washers 121121, and the eyelet 126, the tube being soldered to the eyelet at its midportion and the ends of the tube being beaded over against the dished spring washers 118-418.

The anode disc 122 is preferably made in the form of an annular rim with an apertured central hub integrally joined thereto by two spokes 123-123, as shown in Fig. 4. After the disc has been soldered to the central tube 117, the disc is heavily coated. The preferred form of coating is one application of zinc chromate, a second application of grey enamel, and a third application of White enamel. After the coating has dried, each spoke is scraped bare around its periphery over a maximum width of .05, as shown at 124, these being the areas over which electrolytic action takes place.

The electrode assembly is mounted on a plunger tip 114, the latter being made of one of the well known phenolic condensation products. The plunger tip has a cylindrical body, which conforms to the diameter of the enlarged head 104 of the plunger, a frusto-conical top 115, a cylindrical protuberance 116 on its bottom, and a similar cylindrical protuberance 113 on its frustoconical top 115'. The cylindrical protuberance 116 on the bottom of the plunger tip 114 is received in an axial bore 103 in the plungerhead 104 and the cylindrical protuberance 113 on the top of the plunger tip is received in the central tube 117 of the electrode disc assembly. I

The electrode disc assembly is secured in place through the anode disc 122 which is seated on the shoulder 97 intermediate the counterbore 96 and the enlarged counterbore 98 in the hollow cylindrical extension 80 of the cylindrical casing 78. A retaining ring 83 is positioned on top of the anode disc 122 and the hollow cylindrical extension 80 of the cylindrical casing is beaded over at its top at 84 to secure the retaining ring 83 and the electrode-disc assembly in place.

In operation, the demolition firing device of the present invention is attached to a casing 20 containing a high explosive charge in any suitable manner as by the wire 22. The cylindrical cap 85 containing the desiccating agent 90 is unscrewed and discarded. The safety pin 35 is removed and the demolition charge is then planted in close proximity to or in abutting relation with what ever obstacle it may be desiredto remove, Normallya group of demolition charges 20, respectively provided with the demolition firing devices according to the present invention, will be placed against a number of underwater obstacles and detonated by the explosion of an initiating charge fired by a time delay device or by remote control.

When the demolition charge and the attached demolition firing device are planted in the sea water against the obstacle to be removed, the device is in a safe condition prior to the operation of the electrolytic arming cell. The frusto-conical surface 48 on the shoulder 47 of the firing pin 45 abuts the locking ball 25, the positioning spring 50 is held under compression, and the grooved end 46 of the firing pin projects through the bore 18 in the end disc 10 of the body and abuts the snap diaphragm 36. As long as the locking ball 25 is held down by the cylindrical safety block 32, the firing pin is held backed away from the armed position, the catch spring 52 carried by the firing pin being spaced outwardly from the outer face of the end disc 10 of the body, and the outer end of the firing pin abuts the snap diaphragm 36, holding it in the unoperated position; the snap diaphragm is held firmly in this position and, should a sudden blow or pressure wave be impacted upon the diaphragm, it would be punctured and the device would become a dud.

As stated above, the demolition firing device is maintained in the unarmed condition as long as the safety block 32 holds the locking ball 25 depressed. The safety block 32 is in turn held in the depressed position by both the safety pin 35 and the electrolytic arming cell. The safety pin 35 will be removed at the time of planting the demolition firing device and the associated demolition charge in the sea water. During the arming period the safety block 32 is held in position by the frusto-conical sleeve 99 of the electrolytic arming cell and associated parts. The plunger 108 is held down by the electrode disc assembly, the anode disc 122 being gripped against the shoulder 97 by the retaining ring 83 and the beaded over top flange 84 on the hollow cylindrical extension 80 of the cylindrical casing 78, the frusto-conical compression spring 109, however, biasing the plunger 108 upwardly. In this position the lower end of the plunger 108 is interposed intermediate the locking balls 100-100, the latter being forced outwardly from the ends of the transverse bore 102 in the frusto-conical sleeve 99 and into the toroidal groove 2 in the wall of the frusto-conical bore 91 through the bottom of the cylindrical casing 78 and the central boss 77; the frusto-conical sleeve 99 remains locked in position and, should the locking ball 25 and the safety block 32 start to move upwardly, such movement would be blocked by the safety block abutting the lower face of the frusto-conical sleeve 99, which, as stated, is locked to the boss 77 on the cylindrical casing 78 by the locking balls 100--100 projecting into the frusto-conical groove 52 in the latter, thereby preventing any inward movement of the firing pin 45. It therefore follows that any pressure wave impinging upon the snap diaphragm 36, such as the result of countermining during the arming period, will not be transmitted to the anode disc 122 prior to the expiration of the arming period of the electrolytic cell.

After the demolition firing device has been planted in the sea water, electrolytic action sets in, the sea water assembly, comprising principally the cathode washers 119-l19 and the remainder of the anode disc 122, held together by the central tube 117, will topple off the plunger tip 114; the positioning spring 50 will drive the firing pin inwardly, but the latter will be stopped after a short travel by the catch spring 52 abutting the inner face of the end disc 10 with the end of the firing pin positioned slightly to the right of the plane of the diaphragm as viewed on Fig. 2, and the frusto-conical face 48 of the shoulder 47 on the firing pin 45 will drive the locking ball 25 upwardly which, acting through the rubber diaphragm 30, will force the safety block 32 upwardly, and likewise the frusto-conical sleeve 99, the locking balls 100-100 moving inwardly in the transverse bore 102 through the sleeve due concurrently therewith. Delayed arming periods of nine (9) to ninety (96) minutes may be secured by using anode discs 122 having varying spoke widths and thicknesses and lengths along the spokes of the exposed areas 124. The time delay period also varies according to the salinity and temperature of the sea water in various parts of the ocean.

After the electrolytic arming cell has operated to arm the demolition firing device, the firing pin 45 will be biased inwardly by the positioning spring but held from further inward movement by the catch spring 52, which is positioned in the circumferential groove 46 of the firing pin, abutting the inner face of the end disc 10 of the body in such position that the end of the firing pin 45 is positioned on the opposite side of the dead center position or plane of the snap diaphragm 36. The snap diaphragm 36 is now free to move by elastic deformation. Should a pressure wave of such magnitude now impinge upon the diaphragm that the total pressure, hydrostatic plus kinetic thereon, would exceed a predetermined value such, for example, as nine (9) pounds per square inch, the diaphragm will be deflected inwardly and will snap through the plane position and assume a dished concave position. The elastic snap of the diaphragm 36 from the domed convex to the dished concave position exerts a force of approximately fifty (50) pounds on the head of the firing pin 45. The diaphragm 36 strikes the outer end of the firing pin 45, driving it free of the catch 52, and the firing pin, impelled both by the impact of the diaphragm and the expansive force of the positioning spring 50, is projected inwardly, the rounded inner end 51 of the firing pin striking the percussion priming cap 67 and firing same. The disclike shoulder 49 on the firing pin 45 is jammed against the end disc 68 of the percussion priming cap 67 and the burninggases from the priming cap are ejected through the axial bore 59 and the concentric bore 66 through the elongated extension 64 of the adapter, thereby detonating the blasting cap 69 which is mounted on the shoulder 65 on the end of the elongated extension 64. The blasting cap 69 acts as a detonator and in turn detonates the booster charge 76 in the cylindrical casing 70, and the explosion of the latter sequentially detonates the main demolition charge in the casing 20.

Since the demolition firing device of the present invention is pressure operated, it can, if planted in water of too great a depth, be actuated by hydrostatic pressure alone without the explosion of a nearby master charge. The device will be actuated, for example, by the hydrostatic pressure alone at a depth of twenty (20) to twenty-eight (28 feet and for the most satisfactory operation should be plante? in shallow water at depths less than twelve 12) to fifteen 15) .feet. If the device should be dropped in water twenty-five (25) or more feet deep, with the safety pin 35 removed and the electrolytic arming cell in place, it may fire as the arming cell operates.

While there is shown and described herein a certain preferred embodiment of the invention which gives satisfactory results, many other and varied forms and uses will present themselves to those versed in the art without departing from the spirit'of the invention, and the'invention,

therefore, is not limited either in structure or in use except as indicated by the terms and scope of the appended claims.

The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In an underwater firing device for a demolition charge, the combination of a barrel, a priming cap in said barrel for firing said charge, a pin for firing said cap slideably mounted in said barrel, detent means for releasably retaining said firing pin in spaced relation with respect to said cap, spring means engaging said firing pin for urging the firing pin against the detent means and forcibly into engagement with said cap when the detent is released, locking means including a flexible element releasably engaging said detent means in said pin retaining position thereof, an electrolytic cell arranged to be activated by sea water as the device is submerged and having a 'plurality of cathode members and a severable anode member, plunger means carried by said cell in engagement with said locking means for releasably retaining the flexible element until said plunger in engagement with the detent means has been moved a predetermined amount, said locking means being released by the plunger means as the plunger means is moved said predetermined amount thereby to release the detent means and said firing pin in sequential order when the anode member of said cell is sufficiently decomposed by said activation to be severed, and means for moving said plunger means said predetermined amount as said anode is severed.

2. In an underwater firing device for a demolition charge, the combination of means including a movable firing pin for firing said charge, spring means engaging said firing pin for yieldably urging the firing pin into the firing position, a shoulder formed on said firing pin and engageable by said spring means, detent means releasably engaging said shoulder to lock said pin in spaced relation with respect to said firing position, means including a member releasably locked to said device for maintaining said detent means locked to said pin, ball locking means for releasably locking said member to said device, an electrolytic cell having a severable anode member and a pair of cathode members activated by sea water as the device is submerged, releasing means carried by said cell and yieldably supported on said device in engagement with said ball locking means for releasably retaining the ball locking means in locking engagement with said device and for releasing said locking means to release said member as the releasing means is "actuated to a release position, said ball locking means being operated by said releasing means to said release position as the releasing means is moved a predetermined amount thereby to release the detent means from engagement with said firing pin when the anode member of said cell is sufficiently decomposed by said activation to be severed, and means for moving said ball releasing means said predetermined amount as said anode member is severed.

3. In an underwater firing device for a demolition charge, the combination of a casing having a .barrel formed therein, a priming cap mounted in said barrel, a firing pin for said cap slidably mounted in saidbarrel, a spring mounted in said barrel for yieldably urging said firing pin in the direction of said cap, a ball-shaped detent for releasably retaining said firing pin in spaced relation with respect to the cap and against the action of said spring, locking means including a flexible diaphragm in engagement with said ball-shaped detent for maintaining said ball-shaped detent in locking engagement with said firing pin, an electrolytic cell having a severable anode member and a pair of cathode members activated by sea Water as the device is submerged, plunger means carried by said cell and yieldably supported on said device in engagement with said locking means for releasably retaining the locking means in locking engagement with said ball-shaped detent, said locking means being operated by said plunger means to release the detent as the plunger is moved a predetermined amount thereby to release the firing pin to fire the cap when the anode member is sufiiciently decomposed by said activation to be severed, and resilient means in engagement with said plunger means for moving the plunger said predetermined amount as said anode is severed.

4. An underwater firing device for a demolition charge and having a casing with a bore formed therein comprising, in combination, a priming cap mounted in one end of said bore, a firing pin having a shoulder and slidably mounted in said bore, spring means for urging said firing pin in a direction toward said cap, a detent releasably engaging said shoulder for retaining said pin initially in spaced relation with said cap, locking means for releasably engaging the detent, means including a flexible diaphragm in engagement with said detent and the locking means for maintaining the detent in engagement with said shoulder until said locking means is actuated to a release position, an electrolytic cell having a severable anode member and at least one cathode member arranged for activation by sea water as the device is submerged, plunger means carried by said cell in engagement with said locking means for actuating the locking means to said release position as the plunger is moved a predetermined amount and said anode member is sufficiently decomposed by said activation to be severed whereby said detent is released to cause the spring to move the firing pin into firing engagement with the cap, and resilient means in engagement with said plunger for moving the plunger said predetermined amount as said anode is severed.

5. In an underwater firing device for a demolition charge and having a frame with abarrel therein, the combination of a firing pin for said charge slidably mounted in the barrel and having a shoulder thereon, a priming cap mounted in one end of said barrel, spring means engaging said shoulder for impelling the firing pin in a direction toward said cap, detent means releasably engaging said shoulder for locking the firing pin initially in spaced relation to said cap against the impelling force of said spring means, means including an electrolytic cell having a severable spring biased anode member and a cathode member, said members being arranged to be activated by sea water as the device is submerged thereby to decompose the anode member in a predetermined period of time, and a locking member for said detent means releasably engaged by said anode member, said locking member being released by the spring biased movement of the anode member as the anode member severs from the effects of decomposition and spring biasing, said detent being released as the locking member is released thereby to release the firing pin for movement into firing engagement with said cap.

6. In an underwater firing device for a demolition charge and having a casing with a barrel therein, the combination of a firing pin slidably mounted in said barrel and having a shoulder thereon, a priming cap mounted in one end of said barrel, a spring mounted in said barrel and engaging said shoulder for yieldably urging said firing pin in the direction of said cap, said casing having a bore therein at right angles to said barrel, a detent mounted in said bore and engageable with said shoulder for releasably retaining the pin initially in spaced relation with respect to said charge against the force of said spring, said casing having a tapered bore in axial alignment with said first named bore and having a circular groove intermediate the ends thereof, a tapered locking member mounted in said tapered bore and having mutually intersecting axial and transverse bores formed therein, a pair of balls mounted in said transverse bore and adapted when forced outwardly to extend into said circular groove thereby to lock said locking member to the casing, a pin extending into said axial bore for forcing said pair of balls outwardly into said groove, spring means for yieldably moving said pin out of said axial bore thereby to release the balls, an electrolytic cell having an anode disc and a pair of cathode discs arranged to be activated by sea water when the device is submerged therein, said anode disc having its peripheral portion secured to said casing and its axial portion in engagement with said pin thereby initially to retain said pin in said axial bore against the force of said spring means, said anode disc being adapted to be decomposed sufliciently to sever intermediate its axial and peripheral portions through electrolytic action of the sea water thereon thereby to release said pin, locking member, and detent in sequence to cause movement of the firing pin to fire the cap.

7. An underwater demolition device for firing a container of explosive material comprising, in combination, a cylindrical housing having an axial bore extending therethrough and a transverse bore intersecting said axial bore, a priming cap mounted in said housing at one end thereof, a firing pin having a shoulder intermediate the ends thereof and mounted for sliding movement within said housing, means for urging said firing pin against said priming cap, a first lock mounted for movement in said transverse bore and initially engaging the shoulder of said firing pin to prevent movement thereof toward said priming cap, a second lock engaging said first lock and releasably retaining said first lock, an electrolytic cell engaging said second look, said electrolytic cell comprising an anode and a pair of cathodes adapted to be activated by an electrolyte composed of sea water, said anode releasing said second lock when eroded by the electrolytic action of the sea water, said second lock releasing said first lock, a third lock engaging a circumferential groove in said firing pin, a snap diaphragm in communication with the sea water on one side and adapted to forcibly engage the firing pin when an explosion occurs in the adjacent water, said forcible engagement of said diaphragm with said firing pin causing release of said third lock from the groove thereby to release the firing pin from a cocked position for movement under the action of said urging means into firing engagement with said cap.

8. In an underwater demolition firing device for firing a container of explosive material, a substantially cylindrical casing, a firing pin mounted for sliding motion in said casing and having an enlarged tapered shoulder intermediate the ends thereof, a detent normallyengaging said shoulder whereby the firing pin is retained in a cocked position, ball locking means including a flexible element in engagement with said detent for holding said detent in engagement with said shoulder, an electrolytic cell in said casing, releasing means carried by said cell and yieldably supported on said casing for normally retaining said ball locking means in locking position and for releasing the locking means when the electrolytic cell is decomposed and said releasing means is moved a predetermined amount, and resilient means in engagement with said ball locking means for moving the ball locking means said predetermined amount.

References Cited in the file of this patent UNITED STATES PATENTS 1,535,633 Sperry Apr. 28, 1925 1,780,592 Johansson 7 Nov. 4, 1930 2,243,621 Denoix May 27, 1941 2,422,548 Hebard June 17, 1947 FOREIGN PATENTS 307,066 Germany June 2, 1920 

